The membranes of the luminal epithelial cells of mammalian urinary bladder containing regular arrays of particles in the external surface are being studied biochemically and structurally to determine the nature of the particles and the exact arrangements of lipids and proteins in the intact membrane. The structure of lipid and lipid-protein model membranes is being studied by x-ray diffraction. The effects of n-alkanes with anesthetic properties on the structure of lipid bilayers is included. The functional properties of black lipid membranes constructed of pure lipids with and without added proteins of various kinds are being investigated. The effects of UO2 plus supra 2 on BLMs are being studied. Ligatin is being studied biochemically and functionally. It has been isolated from nerve tissue and shown to be involved in cell-cell interactions. Tropomyosin is under study by electron microscopy and x-ray diffraction. A new antiparallel model of the molecule is being tested. Tubulin is being studied in relation to microtubule formation in vitro by electron microscopy. Communicating junctions isolated from rat liver are being studied by low dose electron microscopy. Three-dimensional analyses utilizing computer image reconstruction techniques are being carried out. The same methods are also being applied to the hexagonal placque membranes isolated from cow bladders.